\nIf you didn’t know, the K24A2\/TSX head isn’t as performancy<\/em> as a Type-S head CFM-wise. Hence why a lot of folks switch over to a Type-S head or simply because they are piecing together a K24 build and need a head. There’s a thread on K20A.org where member DRAG ran the most commonly used stock K-series heads through a CFM flow bench \u00c2 and made a nifty comparison chart (view thread HERE<\/a>).<\/p>\n
![\"\"](\"https:\/\/ff-squad.com\/technet2\/wp-content\/uploads\/k-series-head-cfm-chart-4p.jpg\")
<\/p>\n
Stock-vs-stock CFM flow bench results are as follows from best to meh:<\/p>\n
- \n
- RSP head<\/strong> \/ JDM K20A (FD2) – 1st best flowing cream of the crop \/ best flowing factory head found on the JDM FD2 K20A CTR engine. Rare AF to find in the states. Head looks similar to that of a K20Z3 & K24A2 head w\/side mounted water neck. Also is the only K head that is factory ported – has an ‘NSX’ port job. Usually stamped with “RSP-2” on the head casting.<\/li>\n
- PRB head<\/strong> \/ JDM K20A, K20A2\/K20Z1 – 2nd best flowing head CFM wise. Most common head used for K20\/24 builds. Found on the RSX-S K20A2 & K20Z1 engines & JDM EP3\/DC5 K20A engines. Has front mounted water neck. Typically stamped with “PRB-1” on the head casting.<\/li>\n
- PPA head <\/strong>\/ K24A1 – 3rd best flowing head. Found in the CRV with K24A1. This head isn’t really used for typical street builds persay but people do it. Its more-so used for a drag race vtec killer build since it does not utilize the typical 3-rockers per exhaust & intake nor has the provisions for lost motion assembly use on the exhaust side of the head. Typically stamped with “PPA-x” on head casting. 4piston has done some port job wonders on this head and increased CFM substantially.<\/li>\n
- RBC head<\/strong> \/ K20Z3 – 4th. Found on the 06-11 Civic Si. Shares the same head layout as a K24A2 head w\/side mounted water neck, but doesn’t have the same port angle as K24A2 head nor smaller ports. Typically stamped with “RBC-2” on head casting.<\/li>\n
- RBB head<\/strong> \/ K24A2 – 5th. Found on the 04-08 TSX. Shares same head layout as K20Z3 and FD2 head w\/side mounted water neck but ports are not the same, are smaller and flow weak vs. all heads listed above. Typically stamped with “RBB-2” on head casting.<\/li>\n<\/ul>\n
When swapping a K20A (EP3\/DC5), K20A2, or K20Z1 head onto a K24A1\/A2\/A4 block the following parts are required:<\/strong><\/p>\n
- \n
- CRV \/ K24A1 head gasket – Honda P\/N 12251-PPA-004
\n<\/strong>This gasket matches a K24A’s 87mm bore size \u00c2\u00a0and also shares the same exact coolant passages as a Type-S head gasket + head. You can’t\/don’t want to use K20A2\/Z1 headgasket because it has a smaller 86mm bore size and the gasket will hang into the cylinder bore.<\/li>\n- Remove coolant diverter – if present
\nIf left in place, may cause overheating issues (says the internet). The PRB head isn’t designed nor requires the use of a coolant diverter.<\/li>\n- Use K24A headstuds<\/li>\n
- Use K24A timing chain<\/li>\n<\/ul>\n
\nWhen swapping an RSP or K20Z3 head onto a K24A1\/A2\/A4 block the following parts are required:<\/strong><\/p>\n- \n
- TSX \/ K24A2 headgasket – Acura P\/N 12251-RBB-004
\n<\/strong>This gasket matches the K24A 87mm bore size and has the proper coolant passages for the RSP, K20Z3, and K24A2 heads.<\/li>\n- Coolant diverter MUST be used<\/li>\n
- Use K24A headstuds<\/li>\n
- Use K24A timing chain<\/li>\n<\/ul>\n
<\/p>\n
An easy rule of thumb is that a head gasket matches the head its designed to work with.<\/p>\n
Credits to K20A.org forum & it’s members for information shared in this article.<\/strong><\/p>\n","protected":false},"excerpt":{"rendered":"
I got tired of googling around sifting through posts on what the proper combination of components are required for swapping a K20A2\/Z1\/Z3 head onto a K24A1\/2\/4 block. Thanks to K20A.org…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[25,99,243],"tags":[132,133,136,135,141,142,97,138,144,131,139,145,137,134,143,130,115,101,128,129,140,127,120,121,116,119,124,125,122,123,117,118,126],"class_list":{"0":"post-629","1":"post","2":"type-post","3":"status-publish","4":"format-standard","6":"category-hybrid-articles","7":"category-k-series","8":"category-k-series-tech","9":"tag-12251-ppa-004","10":"tag-12251-rbb-004","11":"tag-86mm","12":"tag-87mm","13":"tag-8th-gen","14":"tag-8th-gen-civic","15":"tag-civic-si","16":"tag-civic-type-r","17":"tag-coolant-diverter","18":"tag-crv","19":"tag-ctr","20":"tag-diverter","21":"tag-fd2","22":"tag-gasket","23":"tag-head","24":"tag-head-gasket","25":"tag-k-series-head","26":"tag-k20a","27":"tag-k20a2","28":"tag-k20z1","29":"tag-k20z3","30":"tag-k24a2","31":"tag-ppa","32":"tag-ppa-1","33":"tag-prb","34":"tag-prb-1","35":"tag-rbb","36":"tag-rbb-2","37":"tag-rbc","38":"tag-rbc-2","39":"tag-rsp","40":"tag-rsp-1","41":"tag-tsx"},"_links":{"self":[{"href":"https:\/\/ff-squad.com\/technet2\/wp-json\/wp\/v2\/posts\/629","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ff-squad.com\/technet2\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/ff-squad.com\/technet2\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/ff-squad.com\/technet2\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/ff-squad.com\/technet2\/wp-json\/wp\/v2\/comments?post=629"}],"version-history":[{"count":1,"href":"https:\/\/ff-squad.com\/technet2\/wp-json\/wp\/v2\/posts\/629\/revisions"}],"predecessor-version":[{"id":2146,"href":"https:\/\/ff-squad.com\/technet2\/wp-json\/wp\/v2\/posts\/629\/revisions\/2146"}],"wp:attachment":[{"href":"https:\/\/ff-squad.com\/technet2\/wp-json\/wp\/v2\/media?parent=629"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ff-squad.com\/technet2\/wp-json\/wp\/v2\/categories?post=629"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ff-squad.com\/technet2\/wp-json\/wp\/v2\/tags?post=629"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
- Remove coolant diverter – if present
- PRB head<\/strong> \/ JDM K20A, K20A2\/K20Z1 – 2nd best flowing head CFM wise. Most common head used for K20\/24 builds. Found on the RSX-S K20A2 & K20Z1 engines & JDM EP3\/DC5 K20A engines. Has front mounted water neck. Typically stamped with “PRB-1” on the head casting.<\/li>\n